1. Field of the Invention
The present invention relates to a blower and the manufacturing method of the same, which is used for a variety of office automation appliances (hereinafter referred to as xe2x80x9cOA appliancesxe2x80x9d).
2. Conventional Art
Conventionally, in the most OA appliances, many electronic parts are accommodated in a casing, so, the electronic parts are threatened to be damaged due to a heat generated from the electronic parts and accumulated in the casing. And, in general, a ventilation hole is provided in a side wall of the casing and where a blower is installed to discharge the heat accumulated in the casing outside in order to avoid the above problems.
As an example of such blower, there is one such as shown in FIG. 4.
In FIG. 4, a casing 1 forms a cylindrical venturi portion 2 (casing 1). Inside the venturi portion 2, there is an inclined surface at a small inclination angle to form an annular projection (throttle portion).
A motor base 3 is molded integrally at a central portion of one end side (lower in FIG. 4) of the venturi portion 2 (casing 1).
The motor base 8 is formed in general from an annular base body 4, a cylindrical bearing box portion 5 provided in hanging from a hole forming portion of the base body 4 and a base flange 6 formed in bending in the same direction with the bearing box portion 5 on a periphery edge portion of the base body 4.
An annular floor 7 (hereinafter referred to as xe2x80x9ccentral floorxe2x80x9d) is formed inside the bearing box portion 5 and partitions the bearing box portion into two chambers (hereinafter referred to as xe2x80x9cthe first chamber at upper in FIG. 4 and the second chamber at lower in FIG. 4xe2x80x9d: signs are omitted).
Bearings (hereinafter referred to suitably as the first, the second bearings 10, 11) are coupled with the bearing box portion 5 in such a manner as they are disposed respectively in the first and second chambers, which support rotatably a shaft (rotor shaft) 12 inserted through a hole (sign is omitted) of the central floor 7 at two positions.
On one end (FIG. 4, lower) of the rotor shaft 12 a stopping ring 13 for preventing the shaft from being pulled out is installed. On the other end (FIG. 4, upper) of the rotor shaft 12, knurling 14 are engraved. A cup-shaped yoke (motor yoke) 15 is held by insert-molding at the portion provided with knurling 14. An impeller 16 is coupled with the motor yoke 15. An impeller 16 is formed cylindrical and comprises an impeller body 17 to be coupled with the motor yoke 15 and a plurality of blades 18 held on the periphery of the impeller body 17.
And, a ring-shaped magnet 19 is fixed on an inner circumferential side of the motor yoke 15, with an adhesive. A stator assembly 20 is fixed outside of the bearing box portion 5. The stator assembly 20 is in general formed of a stator core 21, a coil 22 wound around the stator core 21 and an insulating body 28 interposed between the stator 21 and the coil 22. A printed circuit board (hereinafter referred to as xe2x80x9cPC boardxe2x80x9d) 24 is disposed at one end side (FIG. 4, lower) of the stator assembly 20.
The PC board 24 comprises an electronic circuit (not shown) connected to the coil 22 through a terminal 25 provided on the coil 22. This electronic circuit is adapted to control for rotation of the magnet 19 that is the impeller 16 for rotation by carrying out a current control to the coil 22 due to an electro-magnetic force between the coil 22 and the magnet 19[that is, a rotor consisting of the magnet 19, the motor yoke 15 and the stator assembly 20 (not shown) function as a brushless motor]. Further, the terminal 25 and the PC board 24 are connected by soldering.
In FIG. 4, 26 designates a lead to supply an electric power to the coil 22 through an electronic circuit.
The blower structure mentioned above is adapted to fix the PC board 24 to the stator assembly 20 by soldering the terminal 25 of the coil 22 consisting of the stator assembly 20 to the electronic circuit of PC board 24.
And the substance 30 (for convenience"" sake, called as a board fixing stator assembly) obtained by fixing PC board 24 to the stator assembly 20 is applied with a resin molding 31 by casting type and the obtained one (hereinafter for convenience"" sake, referred to as a resin molded board fixed stator assembly) 32 is adapted to be adhered and fixed to the bearing box portion 5.
In the blower structured above, a blow in an axial direction is generated by the rotation of the blades 18 of the impeller 16 in the venturi portion 2, and the inside of the casing of the OA appliances is cooled by this blow and a damage of electronic parts installed in the OA appliances due to the heat generated is prevented.
Now, it has been desired to increase the productivity of a blower and to lower the manufacturing cost. However, in the above mentioned prior art, the board fixing stator assembly 80 is prepared by applying a resin molding with a casting type is applied, which includes many processes such as a resin casting process, a vacuum treatment process for evacuating air and a heat treatment process for accelerating hardening, and thereby, the productivity has been lowered and to that extent a higher manufacturing cost is invited.
For reference, it is considered to use an injection molding as a means enabling to reduce the number of process comparing with the casting type. However, when employing the injection molding in place of the casting type for the board fixing stator assembly 30, a resin (resin molding 31) thickness of the resin between the stator assembly 20 and the PC board 24 varies enormously, thereby, the PC board 24 is apt to be deformed, damaged and threatened to generate a wire cutting of the electronic circuit due to a sink of the resin (resin molding 31). So that, even if the injection molding is employed, actually the above requirement (for productivity increasing and cost lowering) has not been appropriately responded.
The present invention has been made in the light of the above circumstance to provide a blower which enables to realize an increasing of productivity and lowering of the manufacturing cost without inviting a deformation and a damage, and a manufacturing method thereof.
According to a first aspect of the present invention, in a blower which comprisises a bearing box formed for housing a bearing in the center portion of a cylindrical casing, a rotor held on a shaft supported rotatably on the bearing, a stator consisting of a stator core and a coil and being held on the periphery of the bearing box, a ring-shaped magnet provided on the rotor spaced from the stator at a given gap and a PC board connected to an extracting terminal of the coil, and having an electronic circuit for carrying out a current controlling for the coil, the blower is characterized in that the. extracting terminal is projected out and connected electrically to the PC board to which the stator is injection-molded with a resin and the whole of the PC board is molded with a casting molding.
According to a second aspect of the present invention, in the constitution of the first aspect, the resin molding of the whole PC board is carried out by an injection molding.
According to a third aspect of the present invention, in the constitution of the second aspect, the whole of the PC board is coated or impregnated with a resin and the whole is injection-molded.
According to a fourth aspect of the present invention, in the constitution of the first aspect of the present invention, the molding of the whole of the PC board is carried out with the casting type molding.
According to a fifth aspect of the present invention, in a manufacturing method of a blower in which, a bearing box for housing a bearing in the center portion of a cylindrical casing is formed, a rotor is held on a shaft supported rotatably on the bearing, a stator consisting of a stator core and a coil is held on the periphery of the bearing box, a ring-shaped magnet is provided on the rotor by being spaced at a given gap from the stator and a PC board having an electronic circuit for carrying out a current controlling for the coil is connected to a terminal for extracting coil. the extracting terminal is projected out and the stator is injection-molded with a resin and to the extracted terminal the PC board is connected electrically and the whole of the PC board is molded with a resin.
According to a sixth aspect of the present invention, in the constitution of the fifth aspect, the molding with a resin of the whole of the PC board is carried out by the injection molding.
According to a seventh aspect of the present invention, in sixth aspect after a resin is coated on the whole of the PC board or it is impregnated with a resin, the molding of the whole of the PC board is carried out by the injection molding with a resin.
According to an eighth aspect of the present invention, in the constitution of the fifth aspect of the present invention, the molding of the whole of the PC board is carried out by a casting molding.